Treating biomass

ABSTRACT

Methods and systems are described for processing cellulosic and lignocellulosic materials and useful intermediates and products, such as energy and fuels. For example, irradiating methods and systems are described to aid in the processing of the cellulosic and lignocellulosic materials. The electron beam accelerator has multiple windows foils and these foils are cooled with cooling gas. In one configuration a secondary foil is integral to the electron beam accelerator and in another configuration the secondary foil is part of the enclosure for the biomass conveying system.

This application is a continuation application of U.S. patentapplication Ser. No. 14/434,682, filed on Apr. 9, 2015, which is aNational Stage of International Patent Application No. PCT/US2013/064332filed on Oct. 10, 2013, which claims priority to U.S. ProvisionalApplication Ser. No. 61/711,807 filed on Oct. 10, 2012, and U.S.Provisional Application Ser. No. 61/711,801 filed on Oct. 10, 2012. Theentire disclosures of these applications are incorporated by referenceherein.

BACKGROUND

As demand for petroleum increases, so too does interest in renewablefeedstocks for manufacturing biofuels and biochemicals. The use oflignocellulosic biomass as a feedstock for such manufacturing processeshas been studied since the 1970s. Lignocellulosic biomass is attractivebecause it is abundant, renewable, domestically produced, and does notcompete with food industry uses.

Many potential lignocellulosic feedstocks are available today, includingagricultural residues, woody biomass, municipal waste, oilseeds/cakesand sea weeds, to name a few. At present these materials are either usedas animal feed, biocompost materials are burned in a cogenerationfacility or are landfilled.

Lignocellulosic biomass comprises crystalline cellulose fibrils embeddedin a hemicellulose matrix, surrounded by lignin. This produces a compactmatrix that is difficult to access by enzymes and other chemical,biochemical and biological processes. Cellulosic biomass materials(i.e., biomass material from which the lignin has been removed) is moreaccessible to enzymes and other conversion processes, but even so,naturally-occurring cellulosic materials often have low yields (relativeto theoretical yields) when contacted with hydrolyzing enzymes.Lignocellulosic biomass is even more recalcitrant to enzyme attack.Furthermore, each type of lignocellulosic biomass has its own specificcomposition of cellulose, hemicellulose and lignin.

While a number of methods have been tried to extract structuralcarbohydrates from lignocellulosic biomass, they are either are tooexpensive, produce too low a yield, leave undesirable chemicals in theresulting product, or simply degrade the sugars.

Monosaccharides from renewable biomass sources could become the basis ofchemical and fuels industries by replacing, supplementing orsubstituting petroleum and other fossil feedstocks. However, techniquesneed to be developed that will make these monosaccharides available inlarge quantities and at acceptable purities and prices.

SUMMARY

Described herein are methods for treating a biomass material, where themethod includes passing an electron beam through multiple window foilsand into the biomass material. The multiple window foils can include asystem of cooled window foils.

In another implementation the invention pertains to methods and systemsfor cooling a primary and secondary foil window of a scanning typeelectron beam accelerator.

In one embodiment, the invention pertains to methods and systems forcooling a primary and secondary foil window of a scanning type electronbeam accelerator and irradiating a material (e.g., a biomass material).

A method is provided for producing a treated biomass material, where themethod includes: providing a starting biomass material; and passing anelectron beam through multiple window foils into starting biomassmaterial; thereby producing a treated biomass material. The treatedbiomass material can have a lower level of recalcitrance relative to thestarting biomass material. The multiple window foils can include asystem of gas cooled window foils.

Also provided is a system for cooling multiple single-type window foilsof an electron beam accelerator, where the system includes: a first flowpath for providing a first cooling gas across a primary single-typewindow foil and second flow path for providing a second cooling gasacross a secondary single-type window foil, where the primary andsecondary single-type window foils are positioned with a gap of lessthan about 9 cm between them. Alternately, if the energy of electronbeam accelerator is high, than larger gaps can be used. Gaps as large as75 cm can be used.

Also provided is a method for cooling multiple single-type window foilsof an electron beam accelerator, where the methods includes: passing afirst cooling gas across a primary single-type window foil and passing asecond cooling gas across a secondary single-type window foil, where theprimary and secondary single-type window foils are positioned facingeach other with a gap of less than about 9 cm between them.

The system of gas cooled window foils can include: a primary single-typewindow foil attached to a scanning horn of an electron beam accelerator;a secondary single-type window foil positioned on an atmospheric side ofthe scanning horn; a first flow path providing a first cooling gasacross the primary single-type window foil; a second flow path providinga second cooling gas across the secondary single-type window foil; and agap between the primary single-type window foil and the secondarysingle-type window foil. The system of gas cooled window foils canfurther include: a cooling chamber having an interior volume defined byone or more walls, the primary single-type window foil and the secondarysingle-type window foil, wherein the cooling chamber include: a firstinlet, which allows a first cooling gas to enter the interior volume; anoptional second inlet, which allows optionally a second cooling gas toenter the interior volume; and at least one outlet, which allows thefirst and the second cooling gasses to exit the interior volume. Thecooling chamber can include four walls and the interior volume can beapproximately rectangular prism in shape. The system of gas cooledwindow foils can further include a treatment enclosure with a coversurface, where the enclosure is positioned on a side of the secondarysingle-type window foil opposite the electron beam accelerator. Thesecondary single-type window foil can be mounted on the cover surface.The cover surface can be perpendicular to the electron beam accelerator.The treatment enclosure can have a first opening.

The methods and systems can also include the steps of: conveying thebiomass material through the first opening; positioning the biomassmaterial under the secondary single-type window foil; and irradiatingthe biomass material; thereby producing a treated biomass material. Thetreatment enclosure can include a second opening. The method can includethe step of conveying the treated biomass material out of the treatmentenclosure through the second opening. Positioning the biomass can beinstantaneous, that is, the positioning step can include conveying thematerial on a conveyer belt that is continuously moving.

The method can also include purging the treatment enclosure with aninert gas, or a reactive gas.

The primary single-type window foil can be made from an element selectedfrom the group consisting of: titanium, scandium, vanadium, chromium,nickel, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium,hafnium, tantalum, tungsten, rhenium, platinum, iridium, and alloys ormixtures of any of these.

Alternatively, the secondary single-type window foil can be made from anelement selected from the group consisting of: titanium, scandium,vanadium, chromium, nickel, zirconium, niobium, molybdenum, ruthenium,rhodium, palladium, hafnium, tantalum, tungsten, rhenium, platinum,iridium, beryllium, aluminum, silicon, and alloys or mixtures of any ofthese.

The primary single-type window foil and the secondary single-type windowfoil can be made of the same element, alloy, or mixture, or they can bemade of different elements, alloys, or mixtures. The primary single-typewindow foil or the secondary single-type window foil or both can be madefrom a low Z element. The primary single-type window foil can be madefrom a high Z element and the secondary single-type window foil can bemade from a low Z element.

The primary single-type window foil can be from 10 to 50 microns thick,from 15 to 40 microns thick, from 20 to 30 microns thick, from 5 to 30microns thick, from 8 to 25 microns thick, or from 10 to 20 micronsthick. The single-type window foils can be the same thickness, ordifferent thickness.

The starting biomass material is selected from the group consisting of:cellulosic material, lignocellulosic material, and starchy material. Thebiomass can be paper, paper products, paper waste, wood, particle board,sawdust, agricultural waste, sewage, silage, grasses, wheat straw, ricehulls, bagasse, cotton, jute, hemp, flax, bamboo, sisal, abaca, straw,corn cobs, corn stover, alfalfa, hay, coconut hair, seaweed, algae, andmixtures thereof.

The biomass can be treated with between 10 and 200 Mrad of radiation,between 10 and 75 Mrad of radiation, between 15 and 50 Mrad ofradiation, or between 20 and 35 Mrad of radiation.

The electron beam can include electrons having an energy of about 0.5-10MeV, about 0.8-5 MeV, about 0.8-3 MeV, about 1-3 MeV, or about 1 MeV.

The electron beam can have a beam current of at least about 50 mA, atleast about 60 mA, at least about 70 mA, at least about 80 mA, at leastabout 90 mA, at least about 100 mA, at least about 125 mA, at leastabout 150 mA.

The electron beam can include electrons having an energy of about 1 MeV,and the spacing between the primary single-type window foil and thesecondary single-type window foil can be less than about 30 centimeters.The electron beam can include electrons having an energy of about 1 MeV,and the spacing between the primary single-type window foil and thesecondary single-type window foil can be less than 20 centimeters. Theelectron beam can include electrons having an energy of about 1 MeV, andthe spacing between the primary single-type window foil and thesecondary single-type window foil can be less than 10 centimeters.

Alternatively, the electron beam comprises electrons can have an energyof about 5 MeV, and the spacing between the primary single-type windowfoil and the secondary single-type window foil can be less than 75centimeters. The electron beam comprises electrons can have an energy ofabout 5 MeV, and the spacing between the primary single-type window foiland the secondary single-type window foil can be less than 60centimeters. The electron beam comprises electrons can have an energy ofabout 5 MeV, and the spacing between the primary single-type window foiland the secondary single-type window foil can be less than 50centimeters. The electron beam comprises electrons can have an energy ofabout 5 MeV, and the spacing between the primary single-type window foiland the secondary single-type window foil can be less than 40centimeters. The electron beam comprises electrons can have an energy ofabout 5 MeV, and the spacing between the primary single-type window foiland the secondary single-type window foil can be less than 30centimeters. The electron beam comprises electrons can have an energy ofabout 5 MeV, and the spacing between the primary single-type window foiland the secondary single-type window foil can be less than 20centimeters.

The methods and systems described herein can include a beam stop.

One advantage of the methods and systems discussed herein is that theprocesses are more robust and incur less down time from failure of foilwindows. In particular, multiple window systems greatly reduce thelikelihood of primary window failure/implosion, which can destroyexpensive accelerator parts. Another advantage is that there can be areduction in the production of toxic by-products, relative to someconventional processes. These advantages provide safer and more robustprocessing, e.g., higher and safer throughput in producing usefulproducts. Yet another advantage of some of the methods and systemsdescribed is that cooling of foil windows can done with a high flow rateof cooling gas without disturbing the material targeted for irradiation.Another advantage of some of the methods and systems is that the gapbetween window foils allows for a beam stop to be removable placedbetween the windows.

Implementations of the invention can optionally include one or more ofthe following summarized features. In some implementations, the selectedfeatures can be applied or utilized in any order while in othersimplementations a specific selected sequence is applied or utilized.Individual features can be applied or utilized more than once in anysequence. In addition, an entire sequence, or a portion of a sequence,of applied or utilized features can be applied or utilized once orrepeatedly in any order. In some optional implementations, the featurescan be applied or utilized with different, or where applicable the same,set or varied, quantitative or qualitative parameters as determined by aperson skilled in the art. For example, parameters of the features suchas size, individual dimensions (e.g., length, width, height), locationof, degree (e.g., to what extent such as the degree of recalcitrance)duration, frequency of use, density, concentration, intensity and speedcan be varied or set, where applicable as determined by a person ofskill in the art.

A method irradiating a biomass material by passing an electron beamthrough multiple windows into the biomass material. The recalcitrance ofthe biomass is reduced by the irradiating. At least one of the multiplewindows is a metallic foil. The primary single-type window foil is onthe high vacuum side of the scanning horn of the electron beamaccelerator and a secondary window is positioned on the atmospheric sideof the scanning horn. In one aspect, the primary single type window foiland the secondary window are part of the same electron beam structureand the foils are cooled by cooling gas. In one configuration both theprimary and secondary window foil has cooling gas. In another aspect theprimary window foil is on the vacuum side of the scanning horn of theelectron beam accelerator and there is a treatment enclosure with acover surface, where the enclosure is positioned on a side of thesecondary single-type window foil opposite the electron beamaccelerator, and the secondary single-type window foil is mounted on thecover surface, perpendicular to the electron beam accelerator andmechanically integral to the treatment enclosure.

A method of processing biomass where the biomass is conveyed into afirst opening of the treatment enclosure, positioned under the secondarysingle type window foil and irradiating it, followed by conveying theirradiated biomass out the second opening of the enclosure. The gaseousspace of treatment enclosure can be purged with an inert gas, a reactivegas or mixtures of these.

The window foils may be made from an element selected from the groupconsisting of: titanium, scandium, vanadium, chromium, nickel,zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, hafnium,tantalum, tungsten, rhenium, platinum, iridium, beryllium, aluminum,silicon, and alloys or mixtures of any of these. The window foils may bemade up the same or different elements, or alloys as listed previously.The window foils can be made of a low Z element and the single-typeprimary window can be made of a high Z element. The primary single-typewindow foil is from 10 to 50 microns thick, alternately 15 microns to 40microns, optionally 20 to 30 microns thick. The secondary single-typewindow foil is from 5 to 30 microns thick, alternately 8 microns to 25microns, optionally 10 to 20 microns thick. The window foils may be ofdifferent thickness.

The starting biomass material is selected from the group consisting of:cellulosic material, lignocellulosic material, and starchy material andcan be selected from the group consisting of paper, paper products,paper waste, wood, particle board, sawdust, agricultural waste, sewage,silage, grasses, wheat straw, rice hulls, bagasse, cotton, jute, hemp,flax, bamboo, sisal, abaca, straw, corn cobs, corn stover, alfalfa, hay,coconut hair, seaweed, algae, and mixtures thereof. The biomass istreated with between 10 and 200 Mrad of radiation, optionally 10 to 75Mrad, alternatively 15 to 50 Mrad and further optionally 20 to 35 Mrad.The biomass is treated where the electron beam has an energy of between0.5 to 10 MeV, optionally 0.8 to 5 MeV, alternatively 0.8 to 3 MeV andfurther optionally 1 to 3 MeV. The biomass is treated where the electronbeam has a beam current of at least 50 mA, alternatively, at least 60mA, optionally, at least 70, further optionally at least 80 mA,alternately, at least 90 mA, alternately, at least 100 mA, optionally atleast 125 mA and further optionally at least 150 mA. The biomass istreated with an electron beam with electrons about 1 MeV and the spacingbetween the primary single-type window foil and secondary single-typewindow foil is less than 30 centimeters, alternately, where the spacingis less than 20 centimeters, and optionally where the spacing is lessthan 10 centimeters. Alternately, when the an electron beam withelectrons about 5 MeV and the spacing between the primary single-typewindow foil and secondary single-type window foil is less than 75centimeters, alternately, where the spacing is less than 60 centimeters,and optionally, where the spacing is less than 50 centimeters, andoptionally where the spacing is less than 40 centimeters, andalternately 30 and alternately less than 20 centimeters.

The method of treating where the electron beam accelerator has a beamstop which can be moveable to absorb different levels of electrons. Thebeam stop and its configuration can absorb 10%, 20%, 40%, 60% 80% and96% of the incident electron energy.

Other features and advantages of the methods and systems will beapparent from the following detailed description, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing exemplary processing of biomass materials touseful products.

FIG. 2 is a diagram showing exemplary processing including irradiationof biomass in an inert atmosphere.

FIG. 3 is an illustration of an enclosed conveyor for irradiating abiomass feedstock.

FIG. 4A is a blow up cross section illustration of the enclosed conveyorand scanning horn with cooled windows. FIG. 4B shows a differentconfiguration of the blow up cross section including a beam stop. FIG.4C is a blow up cross section illustration of the enclosed conveyor withthe pivoting beam stop blocking the electrons.

FIG. 5 is a cross section view through the depth of a scanning horn.

DETAILED DESCRIPTION

Described herein is a method for irradiating biomass material, whichfacilitates the conversion of the material into useful products andimproves the yield of those products from the biomass material. Thetreatment methods described herein are therefore useful in producing abiomass feedstock for use in other processes.

The methods disclosed herein can effectively lower the recalcitrancelevel of the biomass material, improving its utility as a feedstock inthe production of useful intermediates and products. The claimed methodsmake the biomass material easier to process by methods such asbioprocessing (e.g., with any microorganism described herein, such as ahomoacetogen or a heteroacetogen, and/or any enzyme described herein),thermal processing (e.g., gasification or pyrolysis) or chemicalprocessing (e.g., acid hydrolysis or oxidation). Biomass materialintended for use as a feedstock can be treated or processed using one ormore of any of the methods described herein, such as mechanicaltreatment, chemical treatment, radiation, sonication, oxidation,pyrolysis or steam explosion. The various treatment systems and methodscan be used in combinations of two, three, or even four or more of thesetechnologies or others described herein and elsewhere.

Saccharified biomass can then be manufactured into various products. Forexample, FIG. 1, shows a process for manufacturing a sugar and otheruseful products (e.g., alcohol). The process can include, for example,optionally mechanically treating a feedstock (step 110), before and/orafter this treatment, treating the feedstock with another physicaltreatment, for example irradiation by the methods described herein, tofurther reduce its recalcitrance (step 112), and saccharifying thefeedstock, to form a sugar solution (step 114). Optionally, the methodmay also include transporting, e.g., by pipeline, railcar, truck orbarge, the solution (or the feedstock, enzyme and water, ifsaccharification is performed en route) to a manufacturing plant (step116). In some cases the saccharified feedstock is further bioprocessed(e.g., fermented) to produce a desired product (step 118) and byproduct(111). The resulting product may in some implementations be processedfurther, e.g., by distillation (step 120). If desired, the steps ofmeasuring lignin content (step 122) and setting or adjusting processparameters based on this measurement (step 124) can be performed atvarious stages of the process, as described in U.S. Pat. App. Pub.2010/0203495 A1, filed on Feb. 11, 2010, the entire disclosure of whichis incorporated herein by reference.

FIG. 2 shows an irradiation process. This process can be part of theprocess described in FIG. 1 or it can be part of a separate process.Initially, biomass can be delivered to a conveyor (150). Optionally, theconveyor can be enclosed. The biomass can be pre-irradiation processedwhile enclosed in the enclosed conveyor or prior to enclosing thematerial in the enclosed conveyor. Advantageously, the biomass on theconveyor when in an treatment enclosure, is protected from rapid aircurrents that can cause the biomass (e.g., fines and dust) to be loftedin the air. This can present an explosion hazard or damage equipment.The biomass can be conveyed through an irradiation zone (e.g., radiationfield) (154). After irradiation, the biomass can be post processed(156). The process can be repeated (e.g., dashed arrow A). Finally theirradiated biomass is removed from the conveyor and either collected forlater processing or sent directly to make useful products.

FIG. 3 shows one embodiment, an enclosed conveying system forirradiating a comminuted biomass. The enclosure has an encloseddistribution system (310), an enclosed conveyor (311), material removalsystem (318) where the irradiated material exits the conveyor and anirradiation vault and a scan horn (322). The electron window foil (notshown) and enclosure window foil (not shown) have window coolers (320)and (326) respectively for blowing air across the surface of thewindows. The enclosed material distribution system (310) distributes thebiomass onto the conveyor and brings the biomass from outside of theirradiation vault into the enclosed stainless steel conveyor withoutgenerating dust outside of the enclosure (e.g., protecting the biomassfrom air from the window cooling system). The distribution system can beequipped with a spreading system (not shown) to evenly distribute thebiomass on the conveyor to a depth of about 0.25 inches. The enclosedremoval system (318) allows the material to fall off of the conveyorbelt without generating dust outside of the enclosure, where thematerial can be collected (e.g., outside the irradiation vault) ordirected elsewhere for further processing. The scan horn window andenclosure window can be brought together, or lined up so that theelectron beams pass thought the scan horn window, through a small gap ofcooling air and then through the enclosure window. For example, theconveyor can be aligned by moving it on casters and then fixing it inplace. For example the casters can be blocked with a permanent break, ablock, and or a depression. The conveyor can also be aligned by othermethods and equipment, for example rails, wheels, pulleys, shims e g, inany combination. In this window arrangement the scan horn window andenclosure window do not touch, so that the remaining gap allows forefficient cooling. The scan horn window is part of the electron beamapparatus and the enclosure window is part of the treatment enclosuresystem.

A cross sectional detailed view of the scan horn and scan horn window ofFIG. 3 are shown in FIG. 4A. The scan horn window cooler (426) andenclosure window cooler (420) blow air at high velocity across thewindows as indicted by the small arrows. The electrons in the electronbeam (430) pass through the vacuum of the scan horn (422) through thescan horn window (428), through the cooling air gap between the scanhorn window and enclosure window, through the enclosure window (429) andimpinge on and penetrate the biomass material (444) on the conveyorsurface (415). The scan horn window is shown as curved towards thevacuum side of the scan horn, for example due to the vacuum. In theembodiment illustrated, the enclosure window is curved towards theconveyed material. The curvature of the windows can help the cooling airpath flow past the window for efficient cooling. The enclosure window ismounted on the cover (412) of the enclosed conveyor. The enclosurewindow is aligned with the cover surface.

FIG. 4B shows a different configuration of the detailed cross sectionview of the enclosed conveyor including a beam stop. A beam stop (440)can be pivotally fixed to the scan horn and is shown in the openposition, e.g., allowing the e-beam to impinge on the conveyed material.FIG. 4C shows the cross sectional blowup of the scan horn and scan hornwindow with a beam stop (440) where the beam stop is in position forblocking the electrons. The cover surface is denoted by 414.

Optionally, the conveying system shown in FIG. 3 can be maintained underan atmosphere of an inert or reactive gas by a gentle purge through aninlet connected to a nitrogen gas source. The inlet can be positioned atdifferent locations, for example, close to the zone where the biomass isirradiated to be more effective in reducing ozone formation if purgingis with an inert gas; or further and downstream of the irradiation if areactive gas is used that is designed to reacted with an irradiatedmaterial.

FIG. 5 is a cross sectional view of another embodiment of two foilswindow extraction system for a scanning electron beam. The primary foilwindow (510) in a scanning horn (520) is shown. The region indicated isa high vacuum area (525). Generally, the primary window is concavetowards the high vacuum area (525). The secondary foil window (530) isflatter but is also concave in the same direction. This curvature helpsprovide structural support to the window and is mechanically strongerthan a flat window. Alternatively the windows can be flat or curved inany direction. Sidewalls (540) and the primary and secondary windows candefine an interior space (550). Since the primary and secondary windowsare connected by sidewalls in this configuration both windows are partof the electron beam apparatus. Electrons (560) travel through bothwindows to impinge on and penetrate the biomass disposed beneath. Afirst inlet on one sidewall (512) is arranged to allow a cooling fluid(e.g., a liquid or a gas) to impinge on the primary window foil. Thecooling fluid runs along the window and then reverses direction onmeeting the far (opposite) wall and flows back generally through thecenter of the interior space as shown and then out through an exhaustport and or outlet (514). A second inlet (516) on the sidewall isarranged to allow cooling fluid to impinge on the secondary window foilin a similar fashion. Optionally more inlets (e.g., 2, 3, 4, 5, 6 ormore) can bring cooling fluid to the primary and secondary windowsurfaces and more than one outlets (e.g., 2, 3, 4, 5, 6 or more) canallow the cooling fluid to exit the interior space. In some embodimentsone or more side walls can even be a mesh, screen or grate with manyopenings through which cooling gas can flow while providing structuralsupport to the windows. The system can include a conveyor, with aconveying surface (570). A material, for example biomass (444), can beconveyed in the direction indicated as a thin pile (574), e.g., about0.25 inches. Electrons irradiated the material as it is conveyed underthe two foil extraction system.

The Windows

The biomass is irradiated as it passes under a window, which isgenerally a metallic foil (e.g., titanium, titanium alloy, aluminumand/or silicon). The window is impermeable to gases, yet electrons canpass with low resistance. The foil windows are preferably between about10 and 100 microns thick (e.g., about 10 microns thick to about 30microns thick, about 15-40 microns, about 20-30 microns, about 5-30microns, about 8-25 microns, about 10-20 microns, about 20-25 micronsthick, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,45, 46, 47, 48, 49, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100microns thick). Thin windows are preferable to thick windows since thinwindows dissipate less energy as an electron beam passes through them(e.g., the resistive heating is less since Power is the product of thesquare of the current and the resistance, P=I²R). Thin windows are alsoless mechanically strong and more likely to fail which causes increasedexpense and more downtime for the equipment. The distance between thefront surface of the primary window foil and back surface of thesecondary window foil is preferably less than 30 cm, more preferablyless than 20 cm, and most preferably less than 10 cm.

The foil window can be cooled by passing air or an inert gas over thewindow. When using an enclosure, it is generally preferred to mount thewindow to the enclosure and to cool the window from the side outside ofthe enclosed conveying system to avoid lofting up any particulates ofthe material being irradiated.

The system can include more than one window, e.g., a primary window anda secondary window. The two windows may form the enclosure to containthe purging gases and/or the cooling gases. The secondary window mayserve a function as a “sacrificial” window, to protect the primarywindow. The electron beam apparatus includes a vacuum between theelectron source and the primary window, and breakage of the primarywindow is likely to cause biomass material to be sucked up into theelectron beam apparatus, resulting in damage, repair costs, andequipment downtime.

The window can be polymer, ceramic, coated ceramic, composite or coatedcomposite. The secondary window can be, for instance, a continuoussheet/roll of polymer or coated polymer, which can be advancedcontinuously or at intervals to provide a clean or new section to serveas the secondary window.

The primary window and the secondary window can be made from the samematerial, or different materials. For instance, the primary window foilcan be made from titanium, scandium, vanadium, chromium, nickel,zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, hafnium,tantalum, tungsten, rhenium, platinum, iridium, or alloys or mixtures ofany of these. The secondary single-type window foil can be made fromtitanium, scandium, vanadium, chromium, nickel, zirconium, niobium,molybdenum, ruthenium, rhodium, palladium, hafnium, tantalum, tungsten,rhenium, platinum, iridium, beryllium, aluminum, silicon, or alloys ormixtures of any of these. The primary and secondary windows can be ofthe same material, mixture of materials, or alloy, or differentmaterials, mixtures of material or alloys. One or both of the windowscan be laminates of the same of different materials, mixtures ofmaterials, or alloys.

One of more of the windows can have a support structure across its face.The term “single-type window”, as used herein, means a window with nosupport structure across its face. The term “double-type window”, asused herein means a window with a support structure across its face,where the support structure effectively divides the surface of thewindow into two parts. Such a double-type window is shown in U.S. Pat.No. 5,877,582 to Nishimura. Additional support structures can also beused.

The primary window foil and the secondary window foil can both be madefrom low Z element. Alternatively, the primary window foil can be madefrom a high Z element, and the secondary window foil can be made from alow Z element.

The embodiments described herein do not preclude the inclusion ofadditional windows, which may have a protective function, or may beincluded to modify the radiation exposure.

The windows can be concave, flat or convex. It is generally preferredthat the window be slightly convex, in a direction away from thedirection of the cooling fluid. This curvature improves the mechanicalstrength of the window and increases the permitted temperature levels aswell as allowing a better flow path for the cooling fluid. On the sideof the scanning horn the curvature tends to be towards the vacuum (e.g.,away from the cooling fluid) due to the vacuum (e.g., about 10⁻⁵ to10⁻¹⁹ torr, about 10⁻⁶ to 10⁻⁹ torr, about 10⁻⁷ to 10⁻⁸ torr).

The cooling of the window and/or concave shape of the window becomeespecially important for high beam currents, for example at least about100 mA electron gun currents (e.g., at least about 110 mA, at leastabout 120 mA, at least about 130 mA, at least about 140 mA, at leastabout 150 mA at least about 200 mA, at least about 500 mA, at leastabout 1000 mA) because resistive heating is approximately related to thesquare of the current as discussed above. The windows can be any shapebut typically are approximately rectangular with a high aspect ratio ofthe width to the length (where the width direction is the same as thewidth of the conveying system perpendicular to the conveying direction,and the length is the same as the direction of conveying). The distanceof the window to the conveyed material can be less than about 10 cm(e.g., less than about 5 cm) and more than about 0.1 cm (e.g., more thanabout 1 cm, more than about 2 cm, more than about 3 cm, more than about4 cm). It is also possible to use multiple windows (e.g., 3, 4, 5, 6 ormore) with different and varied shapes and configured in different ways.For example, a primary or secondary foil window can include one, two ormore windows in the same plane or layered and can include one or moresupport structures. For example, support structures can be a bar or agrid in the same plane and contacting the windows.

In some embodiments, the window that is mounted on the enclosedconveying system is a secondary foil window of a two foil windowextraction system for a scanning electron beam. In other embodimentsthere is no enclosure for conveying the biomass material, e.g., thebiomass is conveyed in air under the irradiation device.

Window Spacing

Although a large spacing between the windows can be advantageous, forexample, for the reasons described above, the large spacing poses somedisadvantages. One disadvantage of a large spacing between windows isthat the electron beams will pass through a larger volume of cooling gaswhich can cause energy losses. For example, a 1 MeV beam loses about 0.2MeV/m of energy, a 5 MeV beam loses about 0.23 MeV/m and a 10 MeV beamloses about 0.26 MeV/m. Therefore with a 1 MeV beam of electrons passingthrough 1 cm of air, the beam loses only 0.2% of its energy, at 10 cm ofair, the beam loses 2% of its energy, at 20 cm this is 4% of its energy,while at 50 cm the energy loss is 10%. Since the electrons also have totravel from the secondary foil window to the biomass through additionalair, the gap between the windows must be carefully controlled.Preferably, energy losses are less that about 20% (e.g., less than 10%,less than 5% or even less than 1%). It is therefore advantageous tominimize the spacing between the windows to decrease energy losses.Optimal spacing (e.g., average spacing) between the windows (e.g.,between the surface side of the electron window foil and the facingsurface of the secondary window foil) for the benefit of cooling asdescribed above and for the benefit of reducing energy loss are lessthan 30 cm (e.g., between about 2 and 20 cm, between about 3 and 20 cm,between about 4 and 20 cm, between about 5 and 20 cm, between about 6and 20 cm, between about 7 and 20 cm, between about 8 and 20 cm, betweenabout 3 and 15 cm, between about 4 and 15 cm, between about 5 and 15 cm,between about 6 and 15 cm, between about 7 and 15 cm, between about 8and 15 cm between about 3 and 10 cm, between about 4 and 10 cm, betweenabout 5 and 10 cm, between about 6 and 10 cm, between about 7 and 10 cm,between about 8 and 10 cm, preferably less than 20 cm, and mostpreferably less than 10 cm.

Alternatively, at higher MeV equipment a greater gap can be tolerated.The higher gap can be as great as 75 cm. In some embodiments supportstructures for the windows can be used across the windows, althoughthese types of structures are less preferred because of energy lossesthat can occur to the electron beam as it strikes these kinds ofstructures.

A large spacing between the windows can be advantageous because itdefines a larger volume between the windows and allows for rapid flowingof a large volume cooling gasses for very efficient cooling. The inletsand outlets are between 1 mm and 120 mm in diameter (e.g., about 2 mm,about 5 mm about 10 mm, about 20 mm, about 50 mm or even about 100 mm).The cooling gas flow can be at between about 500-2500 CFM (e.g., about600 to 2500 CFM, about 700-2500 CFM, about 800 to 2500 CFM, about 1000to 2500 CFM, about 600 to 2000 CFM, about 700-2000 CFM, about 800 to2000 CFM, about 1000 to 2000 CFM, about 600 to 1500 CFM, about 700-1500CFM, about 800 to 1500 CFM, about 1000 to 1500 CFM). In someembodiments, about 50% of the gas is exchanged per about 60 seconds orless (e.g., in about 50 sec or less, in about 30 sec or less, in about10 sec or less, in about 1 sec or less).

Cooling and Purging Gases

The cooling gas in the two foil window extraction system can be a purgegas or a mixture, for example air, or a pure gas. In some embodimentsthe gas is an inert gas such as nitrogen, argon, helium and or carbondioxide. It is preferred to use a gas rather than a liquid since energylosses to the electron beam are minimized. Mixtures of pure gas can alsobe used, either pre-mixed or mixed in line prior to impinging on thewindows or in the space between the windows. The cooling gas can becooled, for example, by using a heat exchange system (e.g., a chiller)and/or by using boil off from a condensed gas (e.g., liquid nitrogen,liquid helium).

When using an enclosure, the enclosed conveyor can also be purged withan inert gas so as to maintain an atmosphere at a reduced oxygen level.Keeping oxygen levels low avoids the formation of ozone which in someinstances is undesirable due to its reactive and toxic nature. Forexample, the oxygen can be less than about 20% (e.g., less than about10%, less than about 1%, less than about 0.1%, less than about 0.01%, oreven less than about 0.001% oxygen). Purging can be done with an inertgas including, but not limited to, nitrogen, argon, helium or carbondioxide. This can be supplied, for example, from a boil off of a liquidsource (e.g., liquid nitrogen or helium), generated or separated fromair in situ, or supplied from tanks. The inert gas can be recirculatedand any residual oxygen can be removed using a catalyst, such as acopper catalyst bed. Alternatively, combinations of purging,recirculating and oxygen removal can be done to keep the oxygen levelslow.

The enclosure can also be purged with a reactive gas that can react withthe biomass. This can be done before, during or after the irradiationprocess. The reactive gas can be, but is not limited to, nitrous oxide,ammonia, oxygen, ozone, hydrocarbons, aromatic compounds, amides,peroxides, azides, halides, oxyhalides, phosphides, phosphines, arsines,sulfides, thiols, boranes and/or hydrides. The reactive gas can beactivated in the enclosure, e.g., by irradiation (e.g., electron beam,UV irradiation, microwave irradiation, heating, IR radiation), so thatit reacts with the biomass. The biomass itself can be activated, forexample by irradiation. Preferably the biomass is activated by theelectron beam, to produce radicals which then react with the activatedor unactivated reactive gas, e.g., by radical coupling or quenching.

Purging gases supplied to an enclosed conveyor can also be cooled, forexample below about 25° C., below about 0° C., below about −40° C.,below about −80° C., below about −120° C. For example, the gas can beboiled off from a compressed gas such as liquid nitrogen or sublimedfrom solid carbon dioxide. As an alternative example, the gas can becooled by a chiller or part of or the entire conveyor can be cooled.

Beam Stops

In some embodiments the systems and methods include a beam stop (e.g., ashutter). For example, the beam stop can be used to quickly stop orreduce the irradiation of material without powering down the electronbeam device. Alternatively the beam stop can be used while powering upthe electron beam, e.g., the beam stop can stop the electron beam untila beam current of a desired level is achieved. The beam stop can beplaced between the primary foil window and secondary foil window. Forexample, the beam stop can be mounted so that it is movable, that is, sothat it can be moved into and out of the beam path. Even partialcoverage of the beam can be used, for example, to control the dose ofirradiation. The beam stop can be mounted to the floor, to a conveyorfor the biomass, to a wall, to the radiation device (e.g., at the scanhorn), or to any structural support. Preferably the beam stop is fixedin relation to the scan horn so that the beam can be effectivelycontrolled by the beam stop. The beam stop can incorporate a hinge, arail, wheels, slots, or other means allowing for its operation in movinginto and out of the beam. The beam stop can be made of any material thatwill stop at least 5% of the electrons, e.g., at least 10%, 20%, 30%,40%, 50%, 60%, 70%, at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%,96%, 97%, 98%, 99% or even about 100% of the electrons. Useful levels ofstopping electrons can be 10%, 20%, 40%, 60%, 80% and 96%

The beam stop can be made of a metal including, but not limited to,stainless steel, lead, iron, molybdenum, silver, gold, titanium,aluminum, tin, or alloys of these, or laminates (layered materials) madewith such metals (e.g., metal-coated ceramic, metal-coated polymer,metal-coated composite, multilayered metal materials).

The beam stop can be cooled, for example, with a cooling fluid such asan aqueous solution or a gas. The beam stop can be partially orcompletely hollow, for example with cavities. Interior spaces of thebeam stop can be used for cooling fluids and gases. The beam stop can beof any shape, including flat, curved, round, oval, square, rectangular,beveled and wedged shapes.

The beam stop can have perforations so as to allow some electronsthrough, thus controlling (e.g., reducing) the levels of radiationacross the whole area of the window, or in specific regions of thewindow. The beam stop can be a mesh formed, for example, from fibers orwires. Multiple beam stops can be used, together or independently, tocontrol the irradiation. The beam stop can be remotely controlled, e.g.,by radio signal or hard wired to a motor for moving the beam into or outof position.

Radiation Sources

The type of radiation determines the kinds of radiation sources used aswell as the radiation devices and associated equipment. The methods,systems and equipment described herein, for example for treatingmaterials with radiation, can utilized sources as described herein aswell as any other useful source.

Sources of gamma rays include radioactive nuclei, such as isotopes ofcobalt, calcium, technicium, chromium, gallium, indium, iodine, iron,krypton, samarium, selenium, sodium, thalium, and xenon.

Sources of X-rays include electron beam collision with metal targets,such as tungsten or molybdenum or alloys, or compact light sources, suchas those produced commercially by Lyncean.

Alpha particles are identical to the nucleus of a helium atom and areproduced by the alpha decay of various radioactive nuclei, such asisotopes of bismuth, polonium, astatine, radon, francium, radium,several actinides, such as actinium, thorium, uranium, neptunium,curium, californium, americium, and plutonium.

Sources for ultraviolet radiation include deuterium or cadmium lamps.Sources for infrared radiation include sapphire, zinc, or selenidewindow ceramic lamps. Sources for microwaves include klystrons, Slevintype RF sources, or atom beam sources that employ hydrogen, oxygen, ornitrogen gases.

Accelerators used to accelerate the particles (e.g., electrons or ions)can be electrostatic DC, e. g. electrodynamic DC, RF linear, magneticinduction linear or continuous wave. For example, various irradiatingdevices may be used in the methods disclosed herein, including fieldionization sources, electrostatic ion separators, field ionizationgenerators, thermionic emission sources, microwave discharge ionsources, recirculating or static accelerators, dynamic linearaccelerators, van de Graaff accelerators, Cockroft Walton accelerators(e.g., PELLETRON® accelerators), LINACS, Dynamitrons (e.g, DYNAMITRON®accelerators), cyclotrons, synchrotrons, betatrons, transformer-typeaccelerators, microtrons, plasma generators, cascade accelerators, andfolded tandem accelerators. For example, cyclotron type accelerators areavailable from IBA, Belgium, such as the RHODOTRON™ system, while DCtype accelerators are available from RDI, now IBA Industrial, such asthe DYNAMITRON®. Other suitable accelerator systems include, forexample: DC insulated core transformer (ICT) type systems, availablefrom Nissin High Voltage, Japan; S-band LINACs, available from L3-PSD(USA), Linac Systems (France), Mevex (Canada), and Mitsubishi HeavyIndustries (Japan); L-band LINACs, available from Iotron Industries(Canada); and ILU-based accelerators, available from Budker Laboratories(Russia). Ions and ion accelerators are discussed in IntroductoryNuclear Physics, Kenneth S. Krane, John Wiley & Sons, Inc. (1988), KrstoPrelec, FIZIKA B 6 (1997) 4, 177-206, Chu, William T., “Overview ofLight-Ion Beam Therapy”, Columbus-Ohio, ICRU-IAEA Meeting, 18-20 Mar.2006, Iwata, Y. et al., “Alternating-Phase-Focused IH-DTL for Heavy-IonMedical Accelerators”, Proceedings of EPAC 2006, Edinburgh, Scotland,and Leitner, C. M. et al., “Status of the Superconducting ECR Ion SourceVenus”, Proceedings of EPAC 2000, Vienna, Austria. Some particleaccelerators and their uses are disclosed, for example, in U.S. Pat. No.7,931,784 to Medoff, the complete disclosure of which is incorporatedherein by reference.

Electrons may be produced by radioactive nuclei that undergo beta decay,such as isotopes of iodine, cesium, technetium, and iridium.Alternatively, an electron gun can be used as an electron source viathermionic emission and accelerated through an accelerating potential.An electron gun generates electrons, which are then accelerated througha large potential (e.g., greater than about 500 thousand, greater thanabout 1 million, greater than about 2 million, greater than about 5million, greater than about 6 million, greater than about 7 million,greater than about 8 million, greater than about 9 million, or evengreater than 10 million volts) and then scanned magnetically in the x-yplane, where the electrons are initially accelerated in the z directiondown the accelerator tube and extracted through a foil window. Scanningthe electron beams is useful for increasing the irradiation surface whenirradiating materials, e.g., a biomass, that is conveyed through thescanned beam. Scanning the electron beam also distributes the thermalload homogenously on the window and helps reduce the foil window rupturedue to local heating by the electron beam. Window foil rupture is acause of significant down-time due to subsequent necessary repairs andre-starting the electron gun.

A beam of electrons can be used as the radiation source. A beam ofelectrons has the advantages of high dose rates (e.g., 1, 5, or even 10Mrad per second), high throughput, less containment, and lessconfinement equipment. Electron beams can also have high electricalefficiency (e.g., 80%), allowing for lower energy usage relative toother radiation methods, which can translate into a lower cost ofoperation and lower greenhouse gas emissions corresponding to thesmaller amount of energy used. Electron beams can be generated, e.g., byelectrostatic generators, cascade generators, transformer generators,low energy accelerators with a scanning system, low energy acceleratorswith a linear cathode, linear accelerators, and pulsed accelerators.

Electrons can also be more efficient at causing changes in the molecularstructure of carbohydrate-containing materials, for example, by themechanism of chain scission. In addition, electrons having energies of0.5-10 MeV can penetrate low density materials, such as the biomassmaterials described herein, e.g., materials having a bulk density ofless than 0.5 g/cm3, and a depth of 0.3-10 cm. Electrons as an ionizingradiation source can be useful, e.g., for relatively thin piles, layersor beds of materials, e.g., less than about 0.5 inch, e.g., less thanabout 0.4 inch, 0.3 inch, 0.25 inch, or less than about 0.1 inch. Insome embodiments, the energy of each electron of the electron beam isfrom about 0.3 MeV to about 2.0 MeV (million electron volts), e.g., fromabout 0.5 MeV to about 1.5 MeV, or from about 0.7 MeV to about 1.25 MeV.Methods of irradiating materials are discussed in U.S. Pat. App. Pub.2012/0100577 A1, filed Oct. 18, 2011, the entire disclosure of which isherein incorporated by reference.

Electron beam irradiation devices may be procured commercially or built.For example elements or components such inductors, capacitors, casings,power sources, cables, wiring, voltage control systems, current controlelements, insulating material, microcontrollers and cooling equipmentcan be purchased and assembled into a device. Optionally, a commercialdevice can be modified and/or adapted. For example, devices andcomponents can be purchased from any of the commercial sources describedherein including Ion Beam Applications (Louvain-la-Neuve, Belgium), NHVCorporation (Japan), the Titan Corporation (San Diego, Calif.), ViviradHigh Voltage Corp (Billeric, Mass.) and/or Budker Laboratories (Russia).Typical electron energies can be 0.5 MeV, 1 MeV, 2 MeV, 4.5 MeV, 7.5MeV, or 10 MeV. Typical electron beam irradiation device power can be 1kW, 5 kW, 10 kW, 20 kW, 50 kW, 60 kW, 70 kW, 80 kW, 90 kW, 100 kW, 125kW, 150 kW, 175 kW, 200 kW, 250 kW, 300 kW, 350 kW, 400 kW, 450 kW, 500kW, 600 kW, 700 kW, 800 kW, 900 kW or even 1000 kW. Accelerators thatcan be used include NHV irradiators medium energy series EPS-500 (e.g.,500 kV accelerator voltage and 65, 100 or 150 mA beam current), EPS-800(e.g., 800 kV accelerator voltage and 65 or 100 mA beam current), orEPS-1000 (e.g., 1000 kV accelerator voltage and 65 or 100 mA beamcurrent). Also, accelerators from NHV's high energy series can be usedsuch as EPS-1500 (e.g., 1500 kV accelerator voltage and 65 mA beamcurrent), EPS-2000 (e.g., 2000 kV accelerator voltage and 50 mA beamcurrent), EPS-3000 (e.g., 3000 kV accelerator voltage and 50 mA beamcurrent) and EPS-5000 (e.g., 5000 and 30 mA beam current).

Tradeoffs in considering electron beam irradiation device powerspecifications include cost to operate, capital costs, depreciation, anddevice footprint. Tradeoffs in considering exposure dose levels ofelectron beam irradiation would be energy costs and environment, safety,and health (ESH) concerns. Typically, generators are housed in a vault,e.g., of lead or concrete, especially for production from X-rays thatare generated in the process. Tradeoffs in considering electron energiesinclude energy costs.

The electron beam irradiation device can produce either a fixed beam ora scanning beam. A scanning beam may be advantageous with large scansweep length and high scan speeds, as this would effectively replace alarge, fixed beam width. Further, available sweep widths of 0.5 m, 1 m,2 m or more are available. The scanning beam is preferred in mostembodiments describe herein because of the larger scan width and reducedpossibility of local heating and failure of the windows.

Subsequent Use of the Feedstocks

Using the methods described herein, a starting biomass material (e.g.,plant biomass, animal biomass, paper, and municipal waste biomass) canbe used as feedstock to produce useful intermediates and products suchas organic acids, salts of organic acids, anhydrides, esters of organicacids and fuels, e.g., fuels for internal combustion engines orfeedstocks for fuel cells. Systems and processes are described hereinthat can use as feedstock cellulosic and/or lignocellulosic materialsthat are readily available, but often can be difficult to process, e.g.,municipal waste streams and waste paper streams, such as streams thatinclude newspaper, kraft paper, corrugated paper or mixtures of these.

In order to convert the feedstock to a form that can be readilyprocessed, the glucan- or xylan-containing cellulose in the feedstockcan be hydrolyzed to low molecular weight carbohydrates, such as sugars,by a saccharifying agent, e.g., an enzyme or acid, a process referred toas saccharification. The low molecular weight carbohydrates can then beused, for example, in an existing manufacturing plant, such as a singlecell protein plant, an enzyme manufacturing plant, or a fuel plant,e.g., an ethanol manufacturing facility.

The feedstock can be hydrolyzed using an enzyme, e.g., by combining thematerials and the enzyme in a solvent, e.g., in an aqueous solution.

Alternatively, the enzymes can be supplied by organisms that break downbiomass, such as the cellulose and/or the lignin portions of thebiomass, contain or manufacture various cellulolytic enzymes(cellulases), ligninases or various small molecule biomass-degradingmetabolites. These enzymes may be a complex of enzymes that actsynergistically to degrade crystalline cellulose or the lignin portionsof biomass. Examples of cellulolytic enzymes include: endoglucanases,cellobiohydrolases, and cellobiases (β-glucosidases).

During saccharification a cellulosic substrate can be initiallyhydrolyzed by endoglucanases at random locations producing oligomericintermediates. These intermediates are then substrates for exo-splittingglucanases such as cellobiohydrolase to produce cellobiose from the endsof the cellulose polymer. Cellobiose is a water-soluble 1,4-linked dimerof glucose. Finally, cellobiase cleaves cellobiose to yield glucose. Theefficiency (e.g., time to hydrolyze and/or completeness of hydrolysis)of this process depends on the recalcitrance of the cellulosic material.

Biomass Material Preparation—Mechanical Treatments

The biomass can be in a dry form, for example with less than about 35%moisture content (e.g., less than about 20%, less than about 15%, lessthan about 10% less than about 5%, less than about 4%, less than about3%, less than about 2% or even less than about 1%). The biomass can alsobe delivered in a wet state, for example as a wet solid, a slurry or asuspension with at least about 10 wt % solids (e.g., at least about 20wt. %, at least about 30 wt. %, at least about 40 wt. %, at least about50 wt. %, at least about 60 wt. %, at least about 70 wt. %).

The processes disclosed herein can utilize low bulk density materials,for example cellulosic or lignocellulosic feedstocks that have beenphysically pretreated to have a bulk density of less than about 0.75g/cm³, e.g., less than about 0.7, 0.65, 0.60, 0.50, 0.35, 0.25, 0.20,0.15, 0.10, 0.05 or less, e.g., less than about 0.025 g/cm³. Bulkdensity is determined using ASTM D1895B. Briefly, the method involvesfilling a measuring cylinder of known volume with a sample and obtaininga weight of the sample. The bulk density is calculated by dividing theweight of the sample in grams by the known volume of the cylinder incubic centimeters. If desired, low bulk density materials can bedensified, for example, by methods described in U.S. Pat. No. 7,971,809to Medoff, the full disclosure of which is hereby incorporated byreference.

In some cases, the pre-irradiation processing includes screening of thebiomass material. Screening can be through a mesh or perforated platewith a desired opening size, for example, less than about 6.35 mm (¼inch, 0.25 inch), (e.g., less than about 3.18 mm (⅛ inch, 0.125 inch),less than about 1.59 mm ( 1/16 inch, 0.0625 inch), is less than about0.79 mm ( 1/32 inch, 0.03125 inch), e.g., less than about 0.51 mm ( 1/50inch, 0.02000 inch), less than about 0.40 mm ( 1/64 inch, 0.015625inch), less than about 0.23 mm (0.009 inch), less than about 0.20 mm (1/128 inch, 0.0078125 inch), less than about 0.18 mm (0.007 inch), lessthan about 0.13 mm (0.005 inch), or even less than about 0.10 mm ( 1/256inch, 0.00390625 inch)). In one configuration, the desired biomass fallsthrough the perforations or screen and thus biomass larger than theperforations or screen are not irradiated. These larger materials can bere-processed, for example by comminuting, or they can simply be removedfrom processing. In another configuration, material that is larger thanthe perforations is irradiated and the smaller material is removed bythe screening process or recycled. In this kind of a configuration, theconveyor itself (for example a part of the conveyor) can be perforatedor made with a mesh. For example, in one particular embodiment thebiomass material may be wet and the perforations or mesh allow water todrain away from the biomass before irradiation.

Screening of material can also be by a manual method, for example by anoperator or mechanoid (e.g., a robot equipped with a color, reflectivityor other sensor) that removes unwanted material. Screening can also beby magnetic screening wherein a magnet is disposed near the conveyedmaterial and the magnetic material is removed magnetically.

Optional pre-processing can include heating the material. For example aportion of the conveyor can be sent through a heated zone. The heatedzone can be created, for example, by IR radiation, microwaves,combustion (e.g., gas, coal, oil, biomass), resistive heating and/orinductive coils. The heat can be applied from at least one side or morethan one side, can be continuous or periodic and can be for only aportion of the material or all the material. For example, a portion ofthe conveying trough can be heated by use of a heating jacket. Heatingcan be, for example, for the purpose of drying the material. In the caseof drying the material, this can also be facilitated, with or withoutheating, by the movement of a gas (e.g., air, oxygen, nitrogen, He, CO₂,Argon) over and/or through the biomass as it is being conveyed.

Optionally, pre-irradiation processing can include cooling the material.Cooling material is described in U.S. Pat. No. 7,900,857 to Medoff, thedisclosure of which in incorporated herein by reference. For example,cooling can be by supplying a cooling fluid, for example water (e.g.,with glycerol), or nitrogen (e.g., liquid nitrogen) to the bottom of theconveying trough. Alternatively, a cooling gas, for example, chillednitrogen can be blown over the biomass materials or under the conveyingsystem.

Another optional pre-irradiation processing can include adding amaterial to the biomass. The additional material can be added by, forexample, by showering, sprinkling and or pouring the material onto thebiomass as it is conveyed. Materials that can be added include, forexample, metals, ceramics and/or ions as described in U.S. Pat. App.Pub. 2010/0105119 A1 (filed Oct. 26, 2009) and U.S. Pat. App. Pub.2010/0159569 A1 (filed Dec. 16, 2009), the entire disclosures of whichare incorporated herein by reference. Optional materials that can beadded include acids and bases. Other materials that can be added areoxidants (e.g., peroxides, chlorates), polymers, polymerizable monomers(e.g., containing unsaturated bonds), water, catalysts, enzymes and/ororganisms. Materials can be added, for example, in pure form, as asolution in a solvent (e.g., water or an organic solvent) and/or as asolution. In some cases the solvent is volatile and can be made toevaporate e.g., by heating and/or blowing gas as previously described.The added material may form a uniform coating on the biomass or be ahomogeneous mixture of different components (e.g., biomass andadditional material). The added material can modulate the subsequentirradiation step by increasing the efficiency of the irradiation,damping the irradiation or changing the effect of the irradiation (e.g.,from electron beams to X-rays or heat). The method may have no impact onthe irradiation but may be useful for further downstream processing. Theadded material may help in conveying the material, for example, bylowering dust levels.

Biomass can be treated as described herein, e.g. with electron beamradiation, while being conveyed. The biomass can be delivered to theconveyor by using, a belt conveyor, a pneumatic conveyor, a screwconveyor, a hopper, a pipe, manually or by combination of these. Thebiomass can, for example, be dropped, poured and/or placed onto theconveyor by any of these methods. In some embodiments the material isdelivered to the conveyor using an enclosed material distribution systemto help maintain a low oxygen atmosphere and/or control dust and fines.Lofted or air suspended biomass fines and dust are undesirable becausethese can form an explosion hazard or damage the window foils.

The material can be leveled to form a uniform thickness between about0.0312 and 5 inches (e.g., between about 0.0625 and 2.000 inches,between about 0.125 and 1 inches, between about 0.125 and 0.5 inches,between about 0.3 and 0.9 inches, between about 0.2 and 0.5 inchesbetween about 0.25 and 1.0 inches, between about 0.25 and 0.5 inches,0.100+/−0.025 inches, 0.150+/−0.025 inches, 0.200+/−0.025 inches,0.250+/−0.025 inches, 0.300+/−0.025 inches, 0.350+/−0.025 inches,0.400+/−0.025 inches, 0.450+/−0.025 inches, 0.500+/−0.025 inches,0.550+/−0.025 inches, 0.600+/−0.025 inches, 0.700+/−0.025 inches,0.750+/−0.025 inches, 0.800+/−0.025 inches, 0.850+/−0.025 inches,0.900+/−0.025 inches, 0.900+/−0.025 inches.

Generally, it is preferred to convey the material as quickly as possiblethrough the electron beam to maximize throughput. For example, thematerial can be conveyed at rates of at least 1 ft/min, e.g., at least 2ft/min, at least 3 ft/min, at least 4 ft/min, at least 5 ft/min, atleast 10 ft/min, at least 15 ft/min, 20, 25, 30, 35, 40, 45, 50 ft/min.The rate of conveying is related to the beam current, for example, for a¼ inch thick biomass and 100 mA, the conveyor can move at about 20ft/min to provide a useful irradiation dosage, at 50 mA the conveyor canmove at about 10 ft/min to provide approximately the same irradiationdosage.

After the biomass material has been conveyed through a treatment area,e.g., a radiation zone, optional post processing can be done. Theoptional post processing can, for example, be any process describedherein. For example, the biomass can be screened, heated, cooled, and/orcombined with additives. Uniquely to post-irradiation, quenching of theradicals can occur, for example, quenching of radicals by the additionof fluids or gases (e.g., oxygen, nitrous oxide, ammonia, liquids),using pressure, heat, and/or the addition of radical scavengers. Forexample, the biomass can be conveyed out of an enclosed conveyor andexposed to a gas (e.g., oxygen) where it is quenched, formingcarboxylated groups. In one embodiment the biomass can be exposed duringirradiation to a reactive gas or fluid. Quenching of biomass that hasbeen irradiated is described in U.S. Pat. No. 8,083,906 to Medoff, theentire disclosure of which is incorporate herein by reference.

If desired, one or more mechanical treatments can be used in addition toirradiation to further reduce the recalcitrance of thecarbohydrate-containing material. These processes can be applied before,during and or after irradiation.

In some cases, the mechanical treatment may include an initialpreparation of the feedstock as received, e.g., size reduction ofmaterials, such as by comminution, e.g., cutting, grinding, shearing,pulverizing or chopping. For example, in some cases, loose feedstock(e.g., recycled paper, starchy materials, or switchgrass) is prepared byshearing or shredding. Mechanical treatment may reduce the bulk densityof the carbohydrate-containing material, increase the surface area ofthe carbohydrate-containing material and/or decrease one or moredimensions of the carbohydrate-containing material.

Alternatively, or in addition, the feedstock material can first bephysically treated by one or more of the other physical treatmentmethods, e.g., chemical treatment, radiation, sonication, oxidation,pyrolysis or steam explosion, and then mechanically treated. Thissequence can be advantageous since materials treated by one or more ofthe other treatments, e.g., irradiation or pyrolysis, tend to be morebrittle and, therefore, it may be easier to further change the structureof the material by mechanical treatment. For example, a feedstockmaterial can be conveyed through ionizing radiation using a conveyor asdescribed herein and then mechanically treated. Chemical treatment canremove some or all of the lignin (for example chemical pulping) and canpartially or completely hydrolyze the material. The methods also can beused with pre-hydrolyzed material. The methods also can be used withmaterial that has not been pre hydrolyzed. The methods can be used withmixtures of hydrolyzed and non-hydrolyzed materials, for example withabout 50% or more non-hydrolyzed material, with about 60% or morenon-hydrolyzed material, with about 70% or more non-hydrolyzed material,with about 80% or more non-hydrolyzed material or even with 90% or morenon-hydrolyzed material.

In addition to size reduction, which can be performed initially and/orlater in processing, mechanical treatment can also be advantageous foropening up, stressing, breaking or shattering thecarbohydrate-containing materials, making the cellulose of the materialsmore susceptible to chain scission and/or disruption of crystallinestructure during the physical treatment.

Methods of mechanically treating the carbohydrate-containing materialinclude, for example, milling or grinding. Milling may be performedusing, for example, a hammer mill, ball mill, colloid mill, conical orcone mill, disk mill, edge mill, Wiley mill, grist mill or other mill.Grinding may be performed using, for example, a cutting/impact typegrinder. Some exemplary grinders include stone grinders, pin grinders,coffee grinders, and burr grinders. Grinding or milling may be provided,for example, by a reciprocating pin or other element, as is the case ina pin mill. Other mechanical treatment methods include mechanicalripping or tearing, other methods that apply pressure to the fibers, andair attrition milling. Suitable mechanical treatments further includeany other technique that continues the disruption of the internalstructure of the material that was initiated by the previous processingsteps.

Mechanical feed preparation systems can be configured to produce streamswith specific characteristics such as, for example, specific maximumsizes, specific length-to-width, or specific surface areas ratios.Physical preparation can increase the rate of reactions, improve themovement of material on a conveyor, improve the irradiation profile ofthe material, improve the radiation uniformity of the material, orreduce the processing time required by opening up the materials andmaking them more accessible to processes and/or reagents, such asreagents in a solution.

The bulk density of feedstocks can be controlled (e.g., increased). Insome situations, it can be desirable to prepare a low bulk densitymaterial, e.g., by densifying the material (e.g., densification can makeit easier and less costly to transport to another site) and thenreverting the material to a lower bulk density state (e.g., aftertransport). The material can be densified, for example from less thanabout 0.2 g/cc to more than about 0.9 g/cc (e.g., less than about 0.3 tomore than about 0.5 g/cc, less than about 0.3 to more than about 0.9g/cc, less than about 0.5 to more than about 0.9 g/cc, less than about0.3 to more than about 0.8 g/cc, less than about 0.2 to more than about0.5 g/cc). For example, the material can be densified by the methods andequipment disclosed in U.S. Pat. No. 7,932,065 to Medoff andInternational Publication No. WO 2008/073186 (which was filed Oct. 26,2007, was published in English, and which designated the United States),the full disclosures of which are incorporated herein by reference.Densified materials can be processed by any of the methods describedherein, or any material processed by any of the methods described hereincan be subsequently densified.

In some embodiments, the material to be processed is in the form of afibrous material that includes fibers provided by shearing a fibersource. For example, the shearing can be performed with a rotary knifecutter.

For example, a fiber source, e.g., that is recalcitrant or that has hadits recalcitrance level reduced, can be sheared, e.g., in a rotary knifecutter, to provide a first fibrous material. The first fibrous materialis passed through a first screen, e.g., having an average opening sizeof 1.59 mm or less ( 1/16 inch, 0.0625 inch), provide a second fibrousmaterial. If desired, the fiber source can be cut prior to the shearing,e.g., with a shredder. For example, when a paper is used as the fibersource, the paper can be first cut into strips that are, e.g., ¼- to½-inch wide, using a shredder, e.g., a counter-rotating screw shredder,such as those manufactured by Munson (Utica, N.Y.). As an alternative toshredding, the paper can be reduced in size by cutting to a desired sizeusing a guillotine cutter. For example, the guillotine cutter can beused to cut the paper into sheets that are, e.g., 10 inches wide by 12inches long.

In some embodiments, the shearing of the fiber source and the passing ofthe resulting first fibrous material through a first screen areperformed concurrently. The shearing and the passing can also beperformed in a batch-type process.

For example, a rotary knife cutter can be used to concurrently shear thefiber source and screen the first fibrous material. A rotary knifecutter includes a hopper that can be loaded with a shredded fiber sourceprepared by shredding a fiber source. The shredded fiber source. In someimplementations, the feedstock is physically treated prior tosaccharification and/or fermentation. Physical treatment processes caninclude one or more of any of those described herein, such as mechanicaltreatment, chemical treatment, irradiation, sonication, oxidation,pyrolysis or steam explosion. Treatment methods can be used incombinations of two, three, four, or even all of these technologies (inany order). When more than one treatment method is used, the methods canbe applied at the same time or at different times. Other processes thatchange a molecular structure of a biomass feedstock may also be used,alone or in combination with the processes disclosed herein.

Mechanical treatments that may be used, and the characteristics of themechanically treated carbohydrate-containing materials, are described infurther detail in U.S. Pat. App. Pub. 2012/01000577 A1, filed Oct. 18,2011, the full disclosure of which is hereby incorporated herein byreference.

Sonication, Pyrolysis, Oxidation, Steam Explosion

If desired, one or more sonication, pyrolysis, oxidative, or steamexplosion processes can be used in addition to irradiation to furtherreduce the recalcitrance of the carbohydrate-containing material. Theseprocesses can be applied before, during and or after irradiation. Theseprocesses are described in detail in U.S. Pat. No. 7,932,065 to Medoff,the full disclosure of which is incorporated herein by reference.

Biomass Processing after Irradiation

After irradiation the biomass may be transferred to a vessel forsaccharification. Alternately, the biomass can be heated after thebiomass is irradiated prior to the saccharification step. The biomasscan be, for example, by IR radiation, microwaves, combustion (e.g., gas,coal, oil, biomass), resistive heating and/or inductive coils. Thisheating can be in a liquid, for example, in water or other water-basedsolvents. The heat can be applied from at least one side or more thanone side, can be continuous or periodic and can be for only a portion ofthe material or all the material. The biomass may be heated totemperatures above 90° C. in an aqueous liquid that may have an acid ora base present. For example, the aqueous biomass slurry may be heated to90 to 150° C., alternatively, 105 to 145° C., optionally 110 to 140° C.or further optionally from 115 to 135° C. The time that the aqueousbiomass mixture is held at the peak temperature is 1 to 12 hours,alternately, 1 to 6 hours, optionally 1 to 4 hours at the peaktemperature. In some instances, the aqueous biomass mixture is acidic,and the pH is between 1 and 5, optionally 1 to 4, or alternately, 2 to3. In other instances, the aqueous biomass mixture is alkaline and thepH is between 6 and 13, alternately, 8 to 12, or optionally, 8 to 11.

Saccharification

The treated biomass materials can be saccharified, generally bycombining the material and a cellulase enzyme in a fluid medium, e.g.,an aqueous solution. In some cases, the material is boiled, steeped, orcooked in hot water prior to saccharification, as described in U.S. Pat.App. Pub. 2012/01000577 A1, filed Oct. 18, 2011.

The saccharification process can be partially or completely performed ina tank (e.g., a tank having a volume of at least 4000, 40,000, or500,000 L) in a manufacturing plant, and/or can be partially orcompletely performed in transit, e.g., in a rail car, tanker truck, orin a supertanker or the hold of a ship. The time required for completesaccharification will depend on the process conditions and thecarbohydrate-containing material and enzyme used. If saccharification isperformed in a manufacturing plant under controlled conditions, thecellulose may be substantially entirely converted to sugar, e.g.,glucose in about 12-96 hours. If saccharification is performed partiallyor completely in transit, saccharification may take longer.

It is generally preferred that the tank contents be mixed duringsaccharification, e.g., using jet mixing as described in InternationalApp. No. PCT/US2010/035331, filed May 18, 2010, which was published inEnglish as WO 2010/135380 and designated the United States, the fulldisclosure of which is incorporated by reference herein.

The addition of surfactants can enhance the rate of saccharification.Examples of surfactants include non-ionic surfactants, such as a Tween®20 or Tween® 80 polyethylene glycol surfactants, ionic surfactants, oramphoteric surfactants.

It is generally preferred that the concentration of the sugar solutionresulting from saccharification be relatively high, e.g., greater than40%, or greater than 50, 60, 70, 80, 90 or even greater than 95% byweight. Water may be removed, e.g., by evaporation, to increase theconcentration of the sugar solution. This reduces the volume to beshipped, and also inhibits microbial growth in the solution.

Alternatively, sugar solutions of lower concentrations may be used, inwhich case it may be desirable to add an antimicrobial additive, e.g., abroad spectrum antibiotic, in a low concentration, e.g., 50 to 150 ppm.Other suitable antibiotics include amphotericin B, ampicillin,chloramphenicol, ciprofloxacin, gentamicin, hygromycin B, kanamycin,neomycin, penicillin, puromycin, streptomycin. Antibiotics will inhibitgrowth of microorganisms during transport and storage, and can be usedat appropriate concentrations, e.g., between 15 and 1000 ppm by weight,e.g., between 25 and 500 ppm, or between 50 and 150 ppm. If desired, anantibiotic can be included even if the sugar concentration is relativelyhigh. Alternatively, other additives with anti-microbial of preservativeproperties may be used. Preferably the antimicrobial additive(s) arefood-grade.

A relatively high concentration solution can be obtained by limiting theamount of water added to the carbohydrate-containing material with theenzyme. The concentration can be controlled, e.g., by controlling howmuch saccharification takes place. For example, concentration can beincreased by adding more carbohydrate-containing material to thesolution. In order to keep the sugar that is being produced in solution,a surfactant can be added, e.g., one of those discussed above.Solubility can also be increased by increasing the temperature of thesolution. For example, the solution can be maintained at a temperatureof 40-50° C., 60-80° C., or even higher.

Sugars

In the processes described herein, for example after saccharification,sugars (e.g., glucose and xylose) can be isolated. For example, sugarscan be isolated by precipitation, crystallization, chromatography (e.g.,simulated moving bed chromatography, high pressure chromatography),centrifugation, extraction, any other isolation method known in the art,and combinations thereof.

Hydrogenation and Other Chemical Transformations

The processes described herein can include hydrogenation. For example,glucose and xylose can be hydrogenated to sorbitol and xylitolrespectively. Hydrogenation can be accomplished by use of a catalyst(e.g., Pt/gamma-Al₂O₃, Ru/C, Raney Nickel, or other catalysts know inthe art) in combination with H₂ under high pressure (e.g., 10 to 12000psi). Other types of chemical transformation of the products from theprocesses described herein can be used, for example production oforganic sugar derived products such (e.g., furfural and furfural-derivedproducts). Chemical transformations of sugar derived products aredescribed in U.S. Prov. App. No. 61/667,481, filed Jul. 3, 2012, thedisclosure of which is incorporated herein by reference in its entirety.

Fermentation

Yeast and Zymomonas bacteria, for example, can be used for fermentationor conversion of sugar(s) to alcohol(s). Other microorganisms arediscussed below. The optimum pH for fermentations is about pH 4 to 7.For example, the optimum pH for yeast is from about pH 4 to 5, while theoptimum pH for Zymomonas is from about pH 5 to 6. Typical fermentationtimes are about 24 to 168 hours (e.g., 24 to 96 hrs) with temperaturesin the range of 20° C. to 40° C. (e.g., 26° C. to 40° C.), howeverthermophilic microorganisms prefer higher temperatures.

In some embodiments, e.g., when anaerobic organisms are used, at least aportion of the fermentation is conducted in the absence of oxygen, e.g.,under a blanket of an inert gas such as N₂, Ar, He, CO₂ or mixturesthereof. Additionally, the mixture may have a constant purge of an inertgas flowing through the tank during part of or all of the fermentation.In some cases, anaerobic condition, can be achieved or maintained bycarbon dioxide production during the fermentation and no additionalinert gas is needed.

In some embodiments, all or a portion of the fermentation process can beinterrupted before the low molecular weight sugar is completelyconverted to a product (e.g., ethanol). The intermediate fermentationproducts include sugar and carbohydrates in high concentrations. Thesugars and carbohydrates can be isolated via any means known in the art.These intermediate fermentation products can be used in preparation offood for human or animal consumption. Additionally or alternatively, thefermentation products can be ground to a appropriate particle size bycomminution.

Jet mixing may be used during fermentation, and in some casessaccharification and fermentation are performed in the same tank.

Nutrients for the microorganisms may be added during saccharificationand/or fermentation, for example the food-based nutrient packagesdescribed in U.S. Pat. App. Pub. 2012/0052536, filed Jul. 15, 2011, thecomplete disclosure of which is incorporated herein by reference.

Fermentation includes the methods and products that are disclosed inU.S. Prov. App. No. 61/579,559, filed Dec. 22, 2012, and U.S. Prov. App.No. 61/579,576, filed Dec. 22, 2012, the contents of both of which areincorporated by reference herein in their entirety.

Mobile fermenters can be utilized, as described in International App.No. PCT/US2007/074028 (which was filed Jul. 20, 2007, was published inEnglish as WO 2008/011598 and designated the United States), thecontents of which is incorporated herein in its entirety. Similarly, thesaccharification equipment can be mobile. Further, saccharificationand/or fermentation may be performed in part or entirely during transit.

Distillation

After fermentation, the resulting fluids can be distilled using, forexample, a “beer column” to separate ethanol and other alcohols from themajority of water and residual solids. The vapor exiting the beer columncan be, e.g., 35% by weight ethanol and can be fed to a rectificationcolumn. A mixture of nearly azeotropic (92.5%) ethanol and water fromthe rectification column can be purified to pure (99.5%) ethanol usingvapor-phase molecular sieves. The beer column bottoms can be sent to thefirst effect of a three-effect evaporator. The rectification columnreflux condenser can provide heat for this first effect. After the firsteffect, solids can be separated using a centrifuge and dried in a rotarydryer. A portion (25%) of the centrifuge effluent can be recycled tofermentation and the rest sent to the second and third evaporatoreffects. Most of the evaporator condensate can be returned to theprocess as fairly clean condensate with a small portion split off towaste water treatment to prevent build-up of low-boiling compounds.

Intermediates and Products

Using the processes described herein, the biomass material can beconverted to one or more products, such as energy, fuels, foods andmaterials. Specific examples of products include, but are not limitedto, hydrogen, sugars (e.g., glucose, xylose, arabinose, mannose,galactose, fructose, disaccharides, oligosaccharides andpolysaccharides), alcohols (e.g., monohydric alcohols or dihydricalcohols, such as ethanol, n-propanol, isobutanol, sec-butanol,tert-butanol or n-butanol), hydrated or hydrous alcohols (e.g.,containing greater than 10%, 20%, 30% or even greater than 40% water),biodiesel, organic acids, hydrocarbons (e.g., methane, ethane, propane,isobutene, pentane, n-hexane, biodiesel, bio-gasoline and mixturesthereof), co-products (e.g., proteins, such as cellulolytic proteins(enzymes) or single cell proteins), and mixtures of any of these in anycombination or relative concentration, and optionally in combinationwith any additives (e.g., fuel additives). Other examples includecarboxylic acids, salts of a carboxylic acid, a mixture of carboxylicacids and salts of carboxylic acids and esters of carboxylic acids(e.g., methyl, ethyl and n-propyl esters), ketones (e.g., acetone),aldehydes (e.g., acetaldehyde), alpha and beta unsaturated acids (e.g.,acrylic acid) and olefins (e.g., ethylene). Other alcohols and alcoholderivatives include propanol, propylene glycol, 1,4-butanediol,1,3-propanediol, sugar alcohols (e.g., erythritol, glycol, glycerol,sorbitol threitol, arabitol, ribitol, mannitol, dulcitol, fucitol,iditol, isomalt, maltitol, lactitol, xylitol and other polyols), andmethyl or ethyl esters of any of these alcohols. Other products includemethyl acrylate, methylmethacrylate, lactic acid, citric acid, formicacid, acetic acid, propionic acid, butyric acid, succinic acid, valericacid, caproic acid, 3-hydroxypropionic acid, palmitic acid, stearicacid, oxalic acid, malonic acid, glutaric acid, oleic acid, linoleicacid, glycolic acid, gamma-hydroxybutyric acid, and mixtures thereof,salts of any of these acids, mixtures of any of the acids and theirrespective salts. Many of the products obtained, such as ethanol orn-butanol, can be utilized as a fuel for powering cars, trucks,tractors, ships or trains, e.g., as an internal combustion fuel or as afuel cell feedstock. Many of the products obtained can also be utilizedto power aircraft, such as planes, e.g., having jet engines orhelicopters. In addition, the products described herein can be utilizedfor electrical power generation, e.g., in a conventional steamgenerating plant or in a fuel cell plant.

Other intermediates and products, including food and pharmaceuticalproducts, are described in U.S. application Ser. No. 12/417,900 filedApr. 3, 2009, the full disclosure of which is hereby incorporated byreference herein.

Carbohydrate Containing Materials (Biomass Materials)

As used herein, the term “biomass materials” is used interchangeablywith the term “carbohydrate-containing materials”, and includeslignocellulosic, cellulosic, starchy, and microbial materials. Any ofthe methods described herein can be practiced with mixtures of anybiomass materials described herein.

Lignocellulosic materials include, but are not limited to, wood,particle board, forestry wastes (e.g., sawdust, aspen wood, wood chips),grasses, (e.g., switchgrass, miscanthus, cord grass, reed canary grass),grain residues, (e.g., rice hulls, oat hulls, wheat chaff, barleyhulls), agricultural waste (e.g., silage, canola straw, wheat straw,barley straw, oat straw, rice straw, jute, hemp, flax, bamboo, sisal,abaca, corn cobs, corn stover, soybean stover, corn fiber, alfalfa, hay,coconut hair), sugar processing residues (e.g., bagasse, beet pulp,agave bagasse), algae, seaweed, manure, sewage, and mixtures of any ofthese.

In some cases, the lignocellulosic material includes corncobs. Ground orhammermilled corncobs can be spread in a layer of relatively uniformthickness for irradiation, and after irradiation are easy to disperse inthe medium for further processing. To facilitate harvest and collection,in some cases the entire corn plant is used, including the corn stalk,corn kernels, and in some cases even the root system of the plant.

Advantageously, no additional nutrients (other than a nitrogen source,e.g., urea or ammonia) are required during fermentation of corncobs orcellulosic or lignocellulosic materials containing significant amountsof corncobs.

Corncobs, before and after comminution, are also easier to convey anddisperse, and have a lesser tendency to form explosive mixtures in airthan other cellulosic or lignocellulosic materials such as hay andgrasses.

Cellulosic materials include, for example, paper, paper products, paperwaste, paper pulp, pigmented papers, loaded papers, coated papers,filled papers, magazines, printed matter (e.g., books, catalogs,manuals, labels, calendars, greeting cards, brochures, prospectuses,newsprint), printer paper, polycoated paper, card stock, cardboard,paperboard, materials having a high α-cellulose content such as cotton,and mixtures of any of these. For example paper products as described inU.S. application Ser. No. 13/396,365 (“Magazine Feedstocks” by Medoff etal., filed Feb. 14, 2012), the full disclosure of which is incorporatedherein by reference.

Cellulosic materials can also include lignocellulosic materials whichhave been de-lignified.

Starchy materials include starch itself, e.g., corn starch, wheatstarch, potato starch or rice starch, a derivative of starch, or amaterial that includes starch, such as an edible food product or a crop.For example, the starchy material can be arracacha, buckwheat, banana,barley, cassava, kudzu, oca, sago, sorghum, regular household potatoes,sweet potato, taro, yams, or one or more beans, such as favas, lentilsor peas. Blends of any two or more starchy materials are also starchymaterials. Mixtures of starchy, cellulosic and or lignocellulosicmaterials can also be used. For example, a biomass can be an entireplant, a part of a plant or different parts of a plant, e.g., a wheatplant, cotton plant, a corn plant, rice plant or a tree. The starchymaterials can be treated by any of the methods described herein.

Microbial materials include, but are not limited to, any naturallyoccurring or genetically modified microorganism or organism thatcontains or is capable of providing a source of carbohydrates (e.g.,cellulose), for example, protists, e.g., animal protists (e.g., protozoasuch as flagellates, amoeboids, ciliates, and sporozoa) and plantprotists (e.g., algae such alveolates, chlorarachniophytes,cryptomonads, euglenids, glaucophytes, haptophytes, red algae,stramenopiles, and viridaeplantae). Other examples include seaweed,plankton (e.g., macroplankton, mesoplankton, microplankton,nanoplankton, picoplankton, and femtoplankton), phytoplankton, bacteria(e.g., gram positive bacteria, gram negative bacteria, andextremophiles), yeast and/or mixtures of these. In some instances,microbial biomass can be obtained from natural sources, e.g., the ocean,lakes, bodies of water, e.g., salt water or fresh water, or on land.Alternatively or in addition, microbial biomass can be obtained fromculture systems, e.g., large scale dry and wet culture and fermentationsystems.

In other embodiments, the biomass materials, such as cellulosic, starchyand lignocellulosic feedstock materials, can be obtained from transgenicmicroorganisms and plants that have been modified with respect to a wildtype variety. Such modifications may be, for example, through theiterative steps of selection and breeding to obtain desired traits in aplant. Furthermore, the plants can have had genetic material removed,modified, silenced and/or added with respect to the wild type variety.For example, genetically modified plants can be produced by recombinantDNA methods, where genetic modifications include introducing ormodifying specific genes from parental varieties, or, for example, byusing transgenic breeding wherein a specific gene or genes areintroduced to a plant from a different species of plant and/or bacteria.Another way to create genetic variation is through mutation breedingwherein new alleles are artificially created from endogenous genes. Theartificial genes can be created by a variety of ways including treatingthe plant or seeds with, for example, chemical mutagens (e.g., usingalkylating agents, epoxides, alkaloids, peroxides, formaldehyde),irradiation (e.g., X-rays, gamma rays, neutrons, beta particles, alphaparticles, protons, deuterons, UV radiation) and temperature shocking orother external stressing and subsequent selection techniques. Othermethods of providing modified genes is through error prone PCR and DNAshuffling followed by insertion of the desired modified DNA into thedesired plant or seed. Methods of introducing the desired geneticvariation in the seed or plant include, for example, the use of abacterial carrier, biolistics, calcium phosphate precipitation,electroporation, gene splicing, gene silencing, lipofection,microinjection and viral carriers. Additional genetically modifiedmaterials have been described in U.S. application Ser. No. 13/396,369filed Feb. 14, 2012 the full disclosure of which is incorporated hereinby reference.

Saccharifying Agents

Suitable cellulolytic enzymes include cellulases from species in thegenera Bacillus, Coprinus, Myceliophthora, Cephalosporium, Scytalidium,Penicillium, Aspergillus, Pseudomonas, Humicola, Fusarium, Thielavia,Acremonium, Chrysosporium and Trichoderma, especially those produced bya strain selected from the species Aspergillus (see, e.g., EP Pub. No. 0458 162), Humicola insolens (reclassified as Scytalidium thermophilum,see, e.g., U.S. Pat. No. 4,435,307), Coprinus cinereus, Fusariumoxysporum, Myceliophthora thermophila, Meripilus giganteus, Thielaviaterrestris, Acremonium sp. (including, but not limited to, A.persicinum, A. acremonium, A. brachypenium, A. dichromosporum, A.obclavatum, A. pinkertoniae, A. roseogriseum, A. incoloratum, and A.furatum). Preferred strains include Humicola insolens DSM 1800, Fusariumoxysporum DSM 2672, Myceliophthora thermophila CBS 117.65,Cephalosporium sp. RYM-202, Acremonium sp. CBS 478.94, Acremonium sp.CBS 265.95, Acremonium persicinum CBS 169.65, Acremonium acremonium AHU9519, Cephalosporium sp. CBS 535.71, Acremonium brachypenium CBS 866.73,Acremonium dichromosporum CBS 683.73, Acremonium obclavatum CBS 311.74,Acremonium pinkertoniae CBS 157.70, Acremonium roseogriseum CBS 134.56,Acremonium incoloratum CBS 146.62, and Acremonium furatum CBS 299.70H.Cellulolytic enzymes may also be obtained from Chrysosporium, preferablya strain of Chrysosporium lucknowense. Additional strains that can beused include, but are not limited to, Trichoderma (particularly T.viride, T. reesei, and T. koningii), alkalophilic Bacillus (see, forexample, U.S. Pat. No. 3,844,890 and EP Pub. No. 0 458 162), andStreptomyces (see, e.g., EP Pub. No. 0 458 162).

Fermentation Agents

The microorganism(s) used in fermentation can be naturally-occurringmicroorganisms and/or engineered microorganisms. For example, themicroorganism can be a bacterium (including, but not limited to, e.g., acellulolytic bacterium), a fungus, (including, but not limited to, e.g.,a yeast), a plant, a protist, e.g., a protozoa or a fungus-like protest(including, but not limited to, e.g., a slime mold), or an alga. Whenthe organisms are compatible, mixtures of organisms can be utilized.

Suitable fermenting microorganisms have the ability to convertcarbohydrates, such as glucose, fructose, xylose, arabinose, mannose,galactose, oligosaccharides or polysaccharides into fermentationproducts. Fermenting microorganisms include strains of the genusSaccharomyces spp. (including, but not limited to, S. cerevisiae(baker's yeast), S. distaticus, S. uvarum), the genus Kluyveromyces,(including, but not limited to, K. marxianus, K. fragilis), the genusCandida (including, but not limited to, C. pseudotropicalis, and C.brassicae), Pichia stipitis (a relative of Candida shehatae), the genusClavispora (including, but not limited to, C. lusitaniae and C.opuntiae), the genus Pachysolen (including, but not limited to, P.tannophilus), the genus Bretannomyces (including, but not limited to,e.g., B. clausenii (Philippidis, G. P., 1996, Cellulose bioconversiontechnology, in Handbook on Bioethanol: Production and Utilization,Wyman, C. E., ed., Taylor & Francis, Washington, D.C., 179-212)). Othersuitable microorganisms include, for example, Zymomonas mobilis,Clostridium spp. (including, but not limited to, C. thermocellum(Philippidis, 1996, supra), C. saccharobutylacetonicum, C.saccharobutylicum, C. Puniceum, C. beijernckii, and C. acetobutylicum),Moniliella pollinis, Yarrowia lipolytica, Aureobasidium sp.,Trichosporonoides sp., Trigonopsis variabilis, Trichosporon sp.,Moniliellaacetoabutans sp., Typhula variabilis, Candida magnoliae,Ustilaginomycetes sp., Pseudozyma tsukubaensis, yeast species of generaZygosaccharomyces, Debaryomyces, Hansenula and Pichia, and fungi of thedematioid genus Torula.

Many such microbial strains are publicly available, either commerciallyor through depositories such as the ATCC (American Type CultureCollection, Manassas, Va., USA), the NRRL (Agricultural Research SeviceCulture Collection, Peoria, Ill., USA), or the DSMZ (Deutsche Sammlungvon Mikroorganismen and Zellkulturen GmbH, Braunschweig, Germany), toname a few.

Commercially available yeasts include, for example, RED STAR®/LesaffreEthanol Red (available from Red Star/Lesaffre, USA), FALI® (availablefrom Fleischmann's Yeast, a division of Burns Philip Food Inc., USA),SUPERSTART® (Lallemand Biofuels and Distilled Spirits, Canada), EAGLE C6FUEL™ or C6 FUEL™ (available from Lallemand Biofuels and DistilledSpirits, Canada), GERT STRAND® (available from Gert Strand AB, Sweden)and FERMOL® (available from DSM Specialties).

Other than in the examples herein, or unless otherwise expresslyspecified, all of the numerical ranges, amounts, values and percentages,such as those for amounts of materials, elemental contents, times andtemperatures of reaction, ratios of amounts, and others, in thefollowing portion of the specification and attached claims may be readas if prefaced by the word “about” even though the term “about” may notexpressly appear with the value, amount, or range. Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thefollowing specification and attached claims are approximations that mayvary depending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains errornecessarily resulting from the standard deviation found in itsunderlying respective testing measurements. Furthermore, when numericalranges are set forth herein, these ranges are inclusive of the recitedrange end points. When percentages by weight are used herein, thenumerical values reported are relative to the total weight.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between (andincluding) the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10. The terms “one,” “a,” or “an”as used herein are intended to include “at least one” or “one or more,”unless otherwise indicated.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. A system for cooling multiple single-type window foils of an electronbeam accelerator comprising: a first flow path for providing a firstcooling gas across a primary single-type window foil and second flowpath for providing a second cooling gas across a secondary single-typewindow foil, wherein the primary and secondary single-type window foilsare positioned with a gap of less than about 9 cm between them.
 2. Thesystem of claim 1, wherein the window foils are metallic.
 3. The systemof claim 1, wherein the primary single-type window foil communicateswith a high vacuum side of a scanning horn of an electron beamaccelerator and the secondary single-type window foil is positioned onan atmospheric side of the scanning horn.
 4. The system of claim 3,wherein both the primary single-type window foil and the secondarysingle-type window foil are part of the scanning horn of the electronbeam accelerator, where at least one inlet is provided and which allowsa cooling gas to enter the gap defined between the primary and thesecondary single-type window foils and at least one outlet is providedto extract cooling gases from the gap defined between the primary andsecondary single-type window foils.
 5. The system of claim 4, furtherincluding a cooling chamber, the cooling chamber including four wallsand the interior volume is approximately rectangular prism in shape. 6.The system of claim 3, further including a treatment enclosure with acover surface, where the enclosure is positioned on a side of thesecondary single-type window foil opposite the electron beamaccelerator.
 7. The system of claim 6, wherein the secondary single-typewindow foil is mounted on the cover surface and is integral to thetreatment enclosure.
 8. The system of claim 7, wherein the cover surfaceis perpendicular to the electron beam accelerator.
 9. The system ofclaim 8, wherein the treatment enclosure has a first opening.
 10. Thesystem of claim 9, further including a conveyor for moving a biomassmaterial through the first opening while positioning the biomassmaterial under the secondary single-type window foil and the electronbeam accelerator irradiates the biomass material.
 11. The system ofclaim 10, wherein the treatment enclosure includes a second opening. 12.The system of claim 11, wherein the conveyor further provides for movingthe treated biomass material out of the treatment enclosure through thesecond opening.
 13. The system of claim 12, further providing forpurging the treatment enclosure with an inert gas.
 14. The system ofclaim 12, further providing for purging the treatment enclosure with areactive gas.
 15. The system of claim 1, wherein the primary single-typewindow foil is made from an element selected from the group consistingof: titanium, scandium, vanadium, chromium, nickel, zirconium, niobium,molybdenum, ruthenium, rhodium, palladium, hafnium, tantalum, tungsten,rhenium, platinum, iridium, and alloys or mixtures of any of these. 16.The system of claim 1, wherein the secondary single-type window foil ismade from an element selected from the group consisting of: titanium,scandium, vanadium, chromium, nickel, zirconium, niobium, molybdenum,ruthenium, rhodium, palladium, hafnium, tantalum, tungsten, rhenium,platinum, iridium, beryllium, aluminum, silicon, and alloys or mixturesof any of these.
 17. The system of claim 1, wherein the primarysingle-type window foil and the secondary single-type window foil aremade of the same element, alloy, or mixture.
 18. The system of claim 1,wherein the primary single-type window foil and the secondarysingle-type window foil are made of different elements, alloys, ormixtures.
 19. The system of claim 1, wherein the primary single-typewindow foil or the secondary single-type window foil or both are madefrom a low Z element.
 20. The system of claim 1, wherein the primarysingle-type window foil is made from a high Z element and the secondarysingle-type window foil is made from a low Z element.
 21. The system ofclaim 1, wherein the primary single-type window foil is from 10 to 50microns thick.
 22. The system of claim 21, wherein the primarysingle-type window foil is from 15 to 40 microns thick.
 23. The systemof claim 21, wherein the primary single-type window foil is from 20 to30 microns thick.
 24. The system of claim 21, wherein the secondarysingle-type window foil is from 5 to 30 microns thick.
 25. The system ofclaim 21, wherein the secondary single-type window foil is from 8 to 25microns thick.
 26. The system of claim 21, wherein the secondarysingle-type window foil is from 10 to 20 microns thick.
 27. The systemof claim 21, wherein the primary single-type window foils are the samethickness.
 28. The system of claim 21, wherein the single-type windowfoils are different thicknesses.
 29. The system of claim 10, wherein thebiomass material is selected from the group consisting of: cellulosicmaterial, lignocellulosic material, and starchy material.
 30. The systemof claim 10, wherein the biomass material is selected from the groupconsisting of paper, paper products, paper waste, wood, particle board,sawdust, agricultural waste, sewage, silage, grasses, wheat straw, ricehulls, bagasse, cotton, jute, hemp, flax, bamboo, sisal, abaca, straw,corn cobs, corn stover, alfalfa, hay, coconut hair, seaweed, algae, andmixtures thereof.
 31. The system of claim 10, wherein the biomassmaterial is treated with between 10 and 200 Mrad of radiation.
 32. Thesystem of claim 10, wherein the biomass material is treated with between10 and 75 Mrad of radiation.
 33. The system of claim 10, wherein thebiomass material is treated with between 15 and 50 Mrad of radiation.34. The system of claim 10, wherein the biomass material is treated withbetween 20 and 35 Mrad of radiation.
 35. The system of claim 3, whereinthe electron beam accelerator includes electrons having an energy ofabout 0.5-10 MeV.
 36. The system of claim 3, wherein the electron beamaccelerator includes electrons having an energy of about 0.8-5 MeV. 37.The system of claim 3, wherein the electron beam accelerator includeselectrons having an energy of about 0.8-3 MeV.
 38. The system of claim3, wherein the electron beam accelerator includes electrons having anenergy of about 1-3 MeV.
 39. The system of claim 3, wherein the electronbeam accelerator includes electrons having an energy of about 1 MeV. 40.The system of claim 3, wherein the electron beam accelerator includes abeam current of at least about 50 mA.
 41. The system of claim 3, whereinthe electron beam accelerator includes a beam current of at least about60 mA.
 42. The system of claim 3, wherein the electron beam acceleratorincludes a beam current of at least about 70 mA.
 43. The system of claim3, wherein the electron beam accelerator includes a beam current of atleast about 80 mA.
 44. The system of claim 3, wherein the electron beamaccelerator includes a beam current of at least about 90 mA.
 45. Thesystem of claim 3, wherein the electron beam accelerator includes a beamcurrent of at least about 100 mA.
 46. The system of claim 3, wherein theelectron beam accelerator includes a beam current of at least about 125mA.
 47. The system of claim 3, wherein the electron beam acceleratorincludes a beam current of at least about 150 mA.
 48. The system ofclaim 3, wherein the electron beam accelerator includes electrons havingan energy of about 1 MeV, and the spacing between the primarysingle-type window foil and the secondary single-type window foil isless than 30 centimeters.
 49. The system of claim 3, wherein theelectron beam accelerator includes electrons having an energy of about 1MeV, and the spacing between the primary single-type window foil and thesecondary single-type window foil is less than 20 centimeters.
 50. Thesystem of claim 3, wherein the electron beam accelerator includeselectrons having an energy of about 1 MeV, and the spacing between theprimary single-type window foil and the secondary single-type windowfoil is less than 10 centimeters.
 51. The system of claim 3, wherein theelectron beam accelerator includes electrons having an energy of about 5MeV, and the spacing between the primary single-type window foil and thesecondary single-type window foil is less than 75 centimeters.
 52. Thesystem of claim 3, wherein the electron beam accelerator includeselectrons having an energy of about 5 MeV, and the spacing between theprimary single-type window foil and the secondary single-type windowfoil is less than 60 centimeters.
 53. The system of claim 3, wherein theelectron beam accelerator includes electrons having an energy of about 5MeV, and the spacing between the primary single-type window foil and thesecondary single-type window foil is less than 50 centimeters.
 54. Thesystem of claim 3, wherein the electron beam accelerator includeselectrons having an energy of about 5 MeV, and the spacing between theprimary single-type window foil and the secondary single-type windowfoil is less than 40 centimeters.
 55. The system of claim 3, wherein theelectron beam accelerator includes electrons having an energy of about 5MeV, and the spacing between the primary single-type window foil and thesecondary single-type window foil is less than 30 centimeters.
 56. Thesystem of claim 3, wherein the electron beam accelerator includeselectrons having an energy of about 5 MeV, and the spacing between theprimary single-type window foil and the secondary single-type windowfoil is less than 20 centimeters.
 57. The system of claim 3, wherein theelectron beam accelerator further includes a beam stop to block anelectron beam of the electron beam accelerator.
 58. The system of claim57, wherein the beam stop is moveable to absorb different amounts of theelectron beam.
 59. The system of claim 57, wherein the beam stop absorbsat least 20% of incident electrons.
 60. The system of claim 57, whereinthe beam stop absorbs at least 40% of incident electrons.
 61. The systemof claim 57, wherein the beam stop absorbs at least 60% of incidentelectrons.
 62. The system of claim 57, wherein the beam stop absorbs atleast 80% of incident electrons.
 63. A method for cooling multiplesingle-type window foils of an electron beam accelerator, the methodcomprising: passing a first cooling gas across a primary single-typewindow foil and passing a second cooling gas across a secondarysingle-type window foil, wherein the primary and secondary single-typewindow foils are positioned facing each other with a gap of less thanabout 9 cm between them.